Confusingly, "geranium" is also the
common name of members of the genus
Pelargonium, which are also in the
family Geraniaceae and are widely grown as horticultural
bedding plants.
Linnaeus originally included all the species in one genus,
Geranium, but they were later separated into two genera by
Charles L’Héritier in 1789. Other former members of the genus are now classified in
Erodium, including the plants known as filarees in North America. The term "hardy geranium" is often applied to horticultural
Geraniums to distinguish them from the
Pelargoniums, which are not winter-hardy in
temperate horticulture. However, not all
Geranium species are winter-hardy (see below). The shape of the flowers offers one way of distinguishing between the two genera
Geranium and
Pelargonium.
Geranium flowers have five very similar petals, and are thus radially symmetrical (
actinomorphic), whereas
Pelargonium (and also
Erodium) flowers have two upper petals which are different from the three lower petals, so the flowers have a single plane of symmetry (
zygomorphic). ==Cultivation==